Magazine article Science News

Poison Source: Toxic Birds May Get Chemical from Beetle

Magazine article Science News

Poison Source: Toxic Birds May Get Chemical from Beetle

Article excerpt

After more than a decade of searching, researchers have found a promising explanation for the defensive chemicals that have been identified in poisonous birds of New Guinea. When the birds eat certain tiny beetles, they may be stocking up on the toxic substance, the scientists suggest.

Birds in the genera Pitohui and Ifrita carry batrachotoxins, the same compounds found in some of the poison frogs of the Americas. Neither the birds nor the frogs are likely to make the toxins themselves, says John P. Dumbacher of the California Academy of Sciences in San Francisco.

He and his colleagues say that after chasing several false leads for sources of toxins in the birds' diets, they have a good candidate: beetles in the little-studied genus Choresine. These beetles, each only about 7 millimeters long, live in the same regions as the birds do and carry batrachotoxins, Dumbacher and his colleagues report in the Nov. 9 Proceedings of the National Academy of Sciences.

They haven't yet traced the poison from beetle to bird, but they note that the birds eat Choresine-size insects. The scientists have also identified a Choresine beetle--though not one of the species tested for toxins so far--in a bird's stomach.

"That's very good circumstantial evidence," comments chemical-ecology pioneer Jerrold Meinwald of the Cornell Institute for Research in Chemical Ecology in Ithaca, N.Y. The batrachotoxins are "very rare compounds, and they occur spottily in nature," he says. …

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